I think the title sums it up. On our PCQ we were quoted $2500 for soakwells, we've just recieved the the contracts and now the soakwells are going to cost $4000. On the PCQ it is states "Site work costs are provisional sums.... based on level, sandy, class A" block. The building hasn't increased in size.
None of the other siteworks costs have increased, so what could account for the extra 60%?